365GTB4

On my 90 ZR1 I need to recharge the Freon. R12 is no longer available in California. Any suggestions?

Thanks in advance,

JW

zr-1 guy

just updated my system to the new stuff last year. expensive but didn't have a choice

Goldcylon

Johnsens R12 Freeze replacement. Never used it but I know its out there. Only other solution is real R-12 or you convert the system to R134-A

zr1fred

Most of the "drop ins" are propane/134 cocktails. They do work. Its far easier to just convert to 134, they sell the kits at nearly all auto parts stores....under $20. We've been doing it for many years here in Arizona with great results, and if it works in Arizona..... You don't need to replace any parts. The problem was with oil compatibility, the new oils take care of that. The only issue is porosity (134 molecules are smaller) which means you may have to add a can every year or so. Even with the availability of R12, most people here just switch, it works nearly as well as R12, better than the "drop ins", and a lot less hassle.

USAZR1

When did GM switch the Corvette to 134?

zr1fred

94, possibly 95.

WydGlydJim

I had a '93 Chevy P/U, and it was the crossover year as some '93s had R12 and some '93s had 134.

VetteMed

If you feel like a road trip to Florida, I have in excess of 20 lbs of R12 on hand

WVZR-1

'94


'94 for Corvettes

Goldcylon

94 was the cross over year

USAZR1

Glad to hear that,one less thing to worry about.

365GTB4

Thanks Vettemed for the offer. I'm not sure the 90 would make it, much less a round trip at this time.

Thanks everybody else for the the comments. I've been running Envirotech in my 64, 66 and 73 for years without any problems but the 90 is a bit of a different animal.

My compressor clutch isn't engaging so I'm assuming there is some kind of pressure sensor in the system that shuts down the compressor if the pressure is to low. I have a vacuum pump and the regular freon filling equipment but I've never tried to fill a system without the compressor running.

Any ideas how this would work with the ZR-1?

VetteMed

The low pressure switch terminals (on the harness connector) need to be jumpered with a wire or paper clip, to allow the compressor to run while charging. Otherwise you'll only be able to add a small amount of refrigerant to the system.

365GTB4

Thanks Vettemed,

I'm traveling right now but I will jump the low pressure switch connector and charge the system this weekend. I was thinking I might change out the switch to a 134r switch as the Enviro-safe refrigerant pressure profile is closer to the 134 freon.

Question, to replace the switch do you have to break into the system?

365GTB4

I put the gauges on the 90 today and no pressure in the system. Big surprise the system has been converted to R134a. I tried the paper clip jumper but the clutch still wouldn't engage.

Any ideas on why the clutch won't engage?

scottfab

Trying to remember how I did all this. It's foggy. I did the R12 to R134 conversion over a decade ago. Seems to me you need to clear the AC error code (error code 9 I think for low pressure) before the clutch is allowed to engage.
Here is one article of a multi-article technote I did back then. Note replacing the accumulator is a MUST when converting. Well, it is if you don't want to be back in there doing it again soon.
Accumulator Replacement
AC Unit Replacement if needed.

erikszr1

I have never ever replaced a pressure switch when converting any system.